1. Field of the Invention
The present invention relates to a coolable piston for internal combustion engines.
2. Description of Related Prior Art
A piston assembly for an internal combustion engine generally becomes very hot during operation. Also, the piston is subjected to relatively severe thermal stresses relative to other engine parts. For example, the crown of the piston is directly exposed to the most extreme heat of the gases in the combustion chamber. The challenges posed by extreme heating of the crown has become more severe with modern internal combustion engines due to increases in the thermal load on the parts resulting from increases in engine power output. Various schemes have been developed in the past for aiding with the cooling of such a piston assembly; some form of active cooling for the piston assembly is often necessary. For example, a flow of lubricant can be directed to the underside of the crown from the crank chamber. It has been recognized as desirable in some arrangements to provide a member near the lower surface of said piston crown to define a lubricant reservoir for temporarily and intermittently accumulating a pool of lubricant. The lubricant from this pool can be splashed against the piston crown as the piston reciprocates in the cylinder bore. Such a lubricant reservoir may be defined by a part of the piston assembly which is integrally formed or cast with the piston main body itself or is welded thereto.